The Liquid Crystal Display (LCD) possesses advantages of thin body, power saving and no radiation to be widely used in many application scope, such as LCD TV, mobile phone, personal digital assistant (PDA), digital camera, notebook, laptop, and dominates the flat panel display field.
Most of the liquid crystal displays on the present market are backlight type liquid crystal displays, which comprise a liquid crystal display panel and a backlight module. The working principle of the liquid crystal display panel is that the Liquid Crystal is injected between the Thin Film Transistor Array Substrate (TFT array substrate) and the Color Filter (CF). The light of backlight module is refracted to generate images by applying driving voltages to the two substrates for controlling the rotations of the liquid crystal molecules.
In the active liquid crystal display, each pixel is electrically coupled to a thin film transistor (TFT), and the gate of the thin film transistor is coupled to a level scan line, and the drain is coupled to a vertical data line, and the source is coupled to the pixel electrode. The enough voltage is applied to the level scan line, and all the TFTs electrically coupled to the horizontal scan line are activated. Thus, the signal voltage on the data line can be written into the pixel to control the transmittances of different liquid crystals to achieve the effect of controlling colors and brightness. The driving of the level scan line in the present active liquid crystal display is mainly accomplished by the external Integrated Circuit (IC). The external IC can control the charge and discharge stage by stage of the level scan lines of respective stages. The GOA (Gate Driver on Array) technology, i.e. the array substrate row driving technology can utilize the array manufacture process of the liquid crystal display panel to manufacture the gate driving circuit on the TFT array substrate for realizing the driving way of scanning the gates row by row. The GOA technology can reduce the bonding procedure of the external IC and has potential to raise the productivity and lower the production cost. Meanwhile, it can make the liquid crystal display panel more suitable to the narrow frame or non frame design of display products.
The GOA circuit according to prior art generally utilizes single way scan, which only can select one of the forward scan and the backward scan. The demands of product diversification cannot be satisfied. Therefore, some GOA circuits with forward-backward scan function are required to be designed.